Chapter 7, Problem 7.94P

(a)

Interpretation Introduction

Interpretation:

A balanced thermochemical equation for the formation of $1.00\text{ mol}$ of glucose is to be determined.

Concept introduction:

Thermochemistry is the branch of chemistry which deals with the energy changes that occur in chemical reactions. The energy changes occur in chemical reactions due to the breakdown of bonds in the reactants and formation of new bonds in the products.

The enthalpy of formation is defined as the amount of energy either absorbed or released during the formation of a compound. The enthalpy of a chemical reaction is the amount of heat either released or absorbed during a chemical reaction.

The general formula to calculate the enthalpy of reaction is,

$\Delta H°=\Sigma \Delta H_f^{°}(\text{products})-\Sigma \Delta H_f^{°}(\text{reactants})$ (1)

The $\Delta H_f^{°}$ values for elements in their standard sates are taken to be zero.

(b)

Interpretation Introduction

Interpretation:

The minimum number of photons with $\lambda =680\text{ nm}$ needed to form $1\text{ mol}$ of glucose, is to be determined.

Concept introduction:

Electromagnetic waves are radiations that are formed by oscillating electric and magnetic fields. The electric and magnetic field components of an electromagnetic wave are perpendicular to each other.

Energy is proportional to the frequency and is expressed by the Plank-Einstein equation as follows:

$E=h\nu$

Here,

$E$ is the energy.

$h$ is the Plank’s constant.

$\nu$ is the frequency.

The equation to relate the frequency and wavelength of electromagnetic radiation is as follows:

$\nu =\frac{c}{\lambda }$

The equation to calculate the energy of a photon is,

$E=h\frac{c}{\lambda }$ (3)

Here,

$c$ is the speed of light.

$\lambda$ is the wavelength.